1. Field of the Invention
This invention relates to jigs and has specific reference to a tool means of this character for drilling and/or tapping in skis the holes to be subsequently engaged by the screws used for fixing ski bindings thereto. The invention is also directed to a method of drilling and tapping these holes in succession.
2. Description of the Prior Art
The tool means now in general use for fixing ski bindings comprise on the one hand a jig associated with a twist bit and on the other hand as crew-tap.
The jig comprises several bit guiding sockets having a relative spacing or distance between centers corresponding to that of the holes formed in the ski binding for the passage of the fixing screws. The jig is provided with retaining members, generally of the jaw type, for safely fastening the jig to the ski during the drilling and/or tapping operation.
As a rule, the twist bit is of the shouldered type, the body being connected to its tip by a shoulder adapted to engage the top surface of the ski upon completion of the drilling step.
On the other hand, the tap consists in most instances of a handle and of a tap bit secured centrally and at right angles thereto, the assembly being substantially T-shaped.
At the end of the drilling operation the jig is removed from the ski.
When self-tapping screws are used, the binding can be secured directly to the ski, since these screws tap their holes directly during the screwing operation.
If conventional screws are used each hole must be tapped. This step is accomplished manually by using a tap.
The jig and drilling method broadly described hereinabove are objectionable on account of the following drawbacks:
Since the presence of a jig conceals the twist drill tip to the operator, the latter becomes aware that the drilling depth is attained when he feels an increased resistance to the drill penetration, this increased resistance corresponding to the engagement between the drill shoulder and the ski surface.
However, this estimation, based on a feeling, that the desired drilling depth is attained, is rather uncertain and likely to be a source of frequent errors. Therefore, some operators are inclined, in a first step, to drill relatively shallow holes and to subsequently remove the jig and complete the drilling operation in a second step during which they can check the drilling progress visually. Though the risks of errors are thus reduced, the time necessary for completing the operation is increased considerably.
Another source of frequent errors is the tapping operation carried out subsequently. In fact, this operation is performed after removing the jig, so that the tap is not guided and its point is likely to engage the hole askew and thus damage this hole, inasmuch as after about each half-turn of the tap the operator must release it, since this tap is actuated and operated in the fashion of a corkscrew.
From the foregoing it is clear that up to now no tool means nor methods have been proposed for rapidly and accurately drilling and tapping holes for fixing ski-bindings to skis unless the operator's skill and experience constitute a determinant factor.
It is the essential object of the present invention to compensate for this insufficiency.